208 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jau. 7, 



segment very prominent, separated from the middle lobe of the gla- 

 bella by a shallow groove. 



We have only one specimen of this species, showing the head. 

 The anterior portion is imperfect, so that the position of the eyes 

 and the development of the ocular ridge cannot be determined. The 

 free part of the cheek is also absent. As in its near neighbours, the 

 neck-segment was probably prolonged and spinous ; but this portion 

 is likewise injured. The head is densely ornamented with tubercles. 



Axis of thorax and abdomen narrow and prominent. Body-rings 

 nine ; lateral portion of body-ring horizontal, convex, with a groove 

 running along it, somewhat nearer the anterior than the posterior 

 margin, and dividing the surface into a narrower anterior and a 

 broader posterior ridge, the posterior ridge terminating in an abruptly 

 reflexed, slightly cilrved spine, nearly one- third the length of the 

 body, and the anterior in a smaller spine, less abruptly reflexed, and 

 so placed as to pass below the posterior spine of the segment before it. 



Tail minute, short, and as wide as the body-rings ; axis of two 

 very convex segments, margin fringed with twelve parallel or slightly 

 approximate equal spines. A ridge runs from the first axis-segment 

 on either side continuous with the antepenultimate spine, indicating 

 the primary spin<^, the posterior spine of the anterior tail- segment. 

 The surface of the body-rings and tail is richly granular. 



This is a pretty, little, distinct species ; the head, body-rings, and 

 tail are nearly equal in breadth, so that the contour of the animal is 

 more regularly a parallelogram than usual. The granulation is pecu- 

 liarly rich, and the long, curved, nearly adpressed spines are graceful. 



A. Jiystrix does not very closely approach any described species. 

 It somewhat resembles A. Prevosti, Barr. The structure of the head 

 and the number and arrangement of the tail-spines distinguish it. 



Locality and Geological Position. — Tolerably common in schists 

 forming the base of the " Graptolite and Orthoceratite flags," Pin- 

 whapple Glen, Ayrshire, = Upper Bala. 



AciDASPis CALLipAREOS, sp. nov. PL VI. figs. 11, 12. 



A. capite magno, transverse, semilunari; scuto centrali fere quadrato, 

 sed antice ahquanto angustiori; glabella magna, tumida, utrinque 

 lobis lateralibus binis, postico majori, oblongo, antico ovato, sulcis 

 circumseptis ; gena convexa, decli\a, margine duodecim circiter stylis 

 parallelis pectinata, postice in spinam fortem producta ; cervice lato, 

 gibbo, (bispinoso?). Thorace — ? Cauda — ? 



We are only acquainted with the head of this beautiful species, 

 which is semicircular and very highly arched. It is -/oths of an inch 

 wide, and belonged to a larger species than either of the foregoing. 



Glabella nearly square, the square defined by the distinct ocular 

 ridge. Side-lobes two, oval, the posterior pair much larger and 

 wider than the anterior ; middle lobe wide and fully arched. Eyes 

 far back in the head, and rather approximate. Portion of cheek 

 without the facial suture, passing nearly perpendicularly downwards 

 from the ocular ridge, ornamented with a beautiful fringe of long 

 parallel spines, and prolonged into a long, curved, genal spine. 



